Update masters after the tryserver split.

jingle/PRESUBMIT.py

Index: jingle/PRESUBMIT.py
diff --git a/jingle/PRESUBMIT.py b/jingle/PRESUBMIT.py
index 4ef2a1b35e273903791f0b0c3019fe1992181533..efa2c486412cf6bfc36f44898280cacef4936766 100644
--- a/jingle/PRESUBMIT.py
+++ b/jingle/PRESUBMIT.py
@@ -10,9 +10,13 @@ for more details on the presubmit API built into gcl.
 
 def GetPreferredTryMasters(project, change):
   return {
-    'tryserver.chromium': {
-      'linux_chromium_rel': set(['defaulttests']),
+    'tryserver.chromium.linux': {
+      'linux_chromium_rel_swarming': set(['defaulttests']),
+    },
+    'tryserver.chromium.mac': {
       'mac_chromium_rel': set(['defaulttests']),
+    },
+    'tryserver.chromium.win': {
       'win_chromium_rel': set(['defaulttests']),
     }
   }